There actually are options to get local SIM cards from Cuba. You cannot buy them though, you have to rent them.There are booths set up at the airport that you can rent Cubacel SIM cards and you may be able to rent them at your hotel.
The Cubacel offices are in Terminals #2 and #3 at José Martí International Airport in Havana open Monday to Sunday 8:30 AM to 7:30 PM.